Given the phenotypic heterogeneity of bipolar disorder, it seems essential to propose new methodologies to improve the stratification of this pathology in order to describe more homogeneous groups of patients. In this perspective, the neurodevelopmental hypothesis of bipolar disorder seems promising. Brain sulcation is an indirect marker of neurodevelopmental processes. The objective of the study is to highlight sulcal variations between a group of bipolar patients with a neurodevelopmental phenotype (ND) and a group of bipolar subjects without a ND phenotype. A sulcation marker (GPR56) will also be measured from patient blood samples. In order to carry out this project we would like to include 120 participants for a period of 12 months.

Inclusion Criteria:

For the "neurodevelopmental" group :

The volunteer has at least 2 of the 12 neurodevelopmental criteria

For the "non-neurodevelopmental" group The volunteer does not present any of the 12 neurodevelopmental criteria

List of the 12 neurodevelopmental criteria :

1. The volunteer had at birth a paternal age ≥ 40 years
2. The volunteer had at birth a maternal age ≥ 35 years
3. The volunteer was born by cesarean section
4. The volunteer had a history of perinatal infection
5. The volunteer has a history of generalized anxiety disorder that began before the age of 16 (≤ 15 years)
6. The volunteer has a history of an eating disorder that began before the age of 16 (≤ 15 years)
7. The volunteer has a history of a substance use disorder (excluding tobacco) as described in the DSM-5 prior to age 16 (≤ 15 years)
8. The volunteer has a learning disability or "dys" disorder as defined in the DSM-5 or number of repeats > 2
9. The volunteer has a history of trauma assessed as severe by the CTQ self-assessment questionnaire
10. The volunteer has symptoms suggestive of Attention Deficit Hyperactivity Disorder (WURS score > 46)
11. The volunteer has a history of psychotic features during episodes.
12. The volunteer has an early age of onset of bipolar disorder at an age below 18 years.

Exclusion Criteria:

• Serious symptomatic or unstable physiological or medical condition (including pregnancy)
• History of stable or non-stable psychiatric illness, schizophrenia or any other condition that may interfere with bipolar disorder
• History of comorbid autism spectrum disorder
• History of severe head injury (GCS<8 at time of injury)
• Neurological disorder affecting central nervous system function
• Moderate to severe substance use disorder (>=4/11 as defined in the DSM-5) with the exception of tobacco use disorder
• Under court protection or guardianship
• Unable to give the volunteer informed information, or the volunteer refuses to sign the consent form
• Insufficient command of the French language to complete the assessments
• Has a contraindication to MRI